This present invention relates to gripping jaw multiple position groove joint pliers wherein, the pivot bolt of the pliers may be slipped in a slot in the shank of one of the plier legs, thereby enabling the jaws to be adjusted to any of several present jaw capacities, and more particularly to the addition of an overtravel stop member on one shank of the pliers and the addition of a variably widened portion to the opposing shank of the pliers, thereby enabling a predetermined safety distance to be maintained between the handles of the pliers in order to prevent hand injury to the user during closing of the handles, making the pliers pinch free in all pivot positions and in all size pliers.
Adjustable gripping jaw multiple position groove joint pliers commonly available comprise a pair of crossed leg members that employ a bolt as the pivot point, however they have a design deficiency that will allow the handles of the pliers to come together and pinch the hand of the user of the pliers in the event the plier jaws accidentally and suddenly slip off of the workpiece they are being used on. Anyone who has ever used groove joint pliers a number of times has probably experienced this mishap. There is no means to limit the inward travel of the plier handles available in the prior art pliers. The present invention comprising a stop device accomplishes protection of the users hand making them pinch free without sacrificing any of the inherent desired operational characteristics of commonly available prior art.
The Vaughan patent 4,271,732 does not accomplish its claims for preventing the closing of the handles without sacrificing inherent desireable operational characteristics of the commonly available prior art multiple position groove joint pliers. Using a 12" pair of pliers as an example, there is not a location that the overtravel stop member can be placed so it will consistently control the closing safety distance. If 3/8" is desired and designed at one pivot position, the closing distance will not be the same in any of the other pivot positions. Consistent control is not possible because of the parallel positioning change that occurs with the handles when a different pivot position of the pliers is selected. The larger the pliers, the greater the discrepancy between the closing distance each position will be. Using a 16" pair of pliers as another example, there is no location that the overtravel stop member can be placed and still maintain an adequate safety closing distance in all pivot positions. This control inadequacy is because the length of the overtravel stop member is limited to that which is necessary to permit the jaws to close and touch in pivot position #1. In some selected positions, this inconsistent control may hold the handles an inordinate distance apart which in turn would reduce the jaw opening range of the selected position. In summation, the overtravel stop member of the Vaughn patent provides inconsistent limiting control on small pliers and does not accomplish the concept of limiting the closing of the handles in larger size pliers.
The Reich patent 4,726,265 does not accomplish its claims for preventing the closing of the handles to a predetermined safety distance without sacrificing inherent desirable operational characteristics of the commonly available prior art multiple position groove joint pliers. These sacrifices are self defeating for application to the prior art. As an example, the stop strip, by being placed on the sliding surface of the slotted shank sacrifices approximately 50% of the arcurate grooves normally present in said shank thereby reducing the maximum jaw capacity of any given size of pliers. A 16" pair of commonly available prior art has a maximum jaw capacity of approximately 41/2"; the same size pliers employing the Reich patent would have a maximum jaw capacity of only approximately 2". The Reich patent drawings FIG. 2 shows that the S safety distance is inordinately wide. As the selected pivot positions are moved up to pivot position #2 from pivot position #5 the S distance increases. Consistent control is not possible because of the parallel positioning change that occurs with the handles when a different pivot position is selected. This inordinately wide distance between the handles reduces the jaw range capacity in each selected position. The placement of the stop member on the sliding surface of the shank with the bolt hole requires that all of the arcurate grooves on one side of the slot of the slotted shank be eliminated; this reduces the bearing surface between the arcurate rib and the arcurate grooves by approximately 50%.